Gael hoffmann



(No Model.)

7 o. HOFPMANN. SYNGHRONIZING DEVICE FOR DYNAMO ELECTRIC MACHINES. No. 396,086. Patented Jan. 15, 1 89.

N PETERS. PiloM-ulhognpher, Wal mflqm n.' a

UNITED STATES PATENT OFFICE,

CARL HOFFMANN, OF BERLIN, GERMANY, ASSIGNOR TO SIEMENS & HALSKE,

' OF SAME PLACE.

SYNCHRONIZING DEVICE FOR DYNAMO ELEC'TRiC MACHiNES.

SPECIFICATION forming part of Letters Patent No. 396,086,

Application filed December 2, 1887. Serial No. 256,830.

dated January 15, 1889,

(No model.) Patented in Germany September 15, 1886, No. 89,680; in

Belgium November 26, 1886, No. 75,380; in France November 29, 1886, No. 179,969, and in Italy December 10, 1886,

GOXLIV, 20,898.

To aZZ whom it may concern.-

Be it known that I, CARL HOFFMANN, a sub j ect of the King of Prussia, German Emperor, residing at the city of Berlin, in the German Empire, have invented new and useful Improvements in Coupling Two or More Alternate-Current Machines with a Main Circuit and Apparatus Therefor, (for which I have obtained Letters Patent in Germany, No. 39,680, dated September 15, 1880; in France, No. 179,969, dated November 29, 1886; in Belgium, No. 75,380, dated November 213, 1880; in Italy, No. 20,898/24si, dated December, 10, 1886,) of which the following is a specification.

If two or more alternate-current machines are required to send into one common external circuit their greatest possible joint current, the resistance of the said circuit being constant, the following conditions must be complied with: First, the difference of potential at the terminals must be of the same value in all machines joined up in quantity; and, secondly, the current impulses must coincide with each other in all machines joined up in quantity. The equalization of the difference of potential at the terminals can be effected by known methods, so that the first question presents no serious difficulty, but the second con dition is not so easy of solution. Experiments have proved that the currents of two ormore alternate-current machines when first joined up in quantity do, as a rule, not coincide, even when the machines are of precisely the same construction and are driven by one and same shaft. Thus any lamps or motors connected to the external circuit: would work veryirregir larly. It is therefore practically not possible to work alternate-current machines in parallel circuit by merely connecting them one after the other with the external circuit, even if the electro-motive force is of the same value in all such machines The present invention has for its object to avoid this difficulty; and it consists in the employment of means whereby the alternatecurrent machines that are to be connected with a circuit already charged by one or more other such machines are automatically placed in the movement when the impulses coincide.

' I attain these objects by the flplfim'zllllS illustrated in the accompanying drawings, which is a sketch of the disposition of said apparatus.

Assuming that one alternatc-current machine, )l, is connected to and charging the external circuit, \C, and that a second one, M is to be parallclly connected when its impulses coincide with the first one, a horseshoe electro-mag'net, E, is employed, the coil S on one leg of which has its two ends connected, respectively, to the two leads, L and L of the external circuit, while the coil S on the other leghas its one end connected to the one lead L of the external circuit and its other end connected to the one terminal of th e second machine, M whose other terminal is connected to the same lead L of the external circuit as that to which the one end of the last-named coil, S is connected, so that the coil of the second leg is practically connected with both ends to the two terminals of the second ma chine, M

The electro-magnet has an armature, A, kept away therefrom by a spring, F, or weight, which armature is electrically connected with that terminal of the second machine, M which is directly connected to the coil 8 011 the second leg of the magnet, while (the arnlature by the electro-mag'nct being attracted) it is caused to make a contact between the said armature and a cup, )2, filled with mercury or a metallic plate or point, whereby the said terminal of the second machine is directly connected to the second lead, It, oi, the external circuit, thus puttingthe second machine in circuit. Before this takes place the coil on the firstnamed leg of the elcctro-magnct has a current passing through it which is derived from that of the first machine, and which is proportional to the dilterencc of potential between the two leads of. the external circui1, while the current passing; through the coil of the second leg is proportional to the difference oil potential between the two terminals of the second machine. So long as the current impulses of the two machines do not co incide the magnetic effects of the two legs of the magnet will to a certain extent be op posed to and consequently weaken each other 5 but as soon as the impulses of the second machine coincide with those of the first one the currents passing through the two coils of the electro-magnet will increase the power of the magnet sufficiently to overcome the resistance of the spring or the weight keeping back the armature, so that this in being attracted will eitect the putting in circuit of the second machine, as described. Thereby the two coils of the electro-magnet will be put in circuit too, and the armature will remain permanently attracted. In the same manner one and the same electro-magnetic apparatus may be used to connect in parallel two or more alternate-current machines with the external circuit in the moment when their impulses coincide by connecting one terminal of such machines to the common external circuit, while the other terminal thereof is connected to the arm'ature A, as shown in the drawing; or there may be a separate apparatus provided for each machine which is to be put in circuit.

Instead of the electro-magnet with two legs, one with a single leg may be employed, having two separate coils connected as before described; also, instead of an electro-magnet and armature, there may be employed a solenoid with two coils and a movable iron core; or two solenoids without cores may be used, so arranged that when the coincidence of the impulses occurs a mutual attraction or repulsion takes place suflieient to overcome the resistance of a spring or a weight.

I claim- 1 1. In an automatic coupler for alternate dynamo-electric machines, the combination, with a main circuit and auxiliary generator, of a magnet providedwith two coils, one of the said coils being included in. the main circuit and the other ot' the said coils being included in the circuit ot' the auxiliary generator, and an armature adapted when moved by the said coils to include the said auxiliary generator in the main circuit, as and for the purpose described.

2. In an automatic coupler for alternatedynamo-electric machines, the combination of a main external circuit, an auxiliary generator, a magnet, coils surrounding the said magnet, one of the said coils having its ends connected to the main external circuit, the other of the said coils having its ends connected with the poles of the auxiliary generator, and an armature provided with a retracting device, adapted to include the auxiliary generator in the main circuit when moved by the said magnet, as and for the purpose described, and substantially as set forth.

3. In an automatic coupler for alternatedynamo-electric machines, the combination of a main external circuit, an auxiliary generator, a magnet, coils surrounding the same, one of the said coils having its ends connected to the main external circuit, the other of the said coils having its ends connected with the poles of the auxiliary generator, and an armature electrically connected with the said auxiliary generator and adapted when. moved by the said magnets to include the said generator in the main circuit at the time their impulses coincide, as and for the purpose described.

a. In an automatic coupler for alternate electrical generators, the combination, with a main circuit and an auxiliary alternate generator, of a magnet provided with an armature adapted to include the said generator in the main circuit at the moment their impulses coincide, as and for the purpose described.

5. In an automatic coupler for electrical. generators, the combination of a main external circuit, consisting of two leads, L and L an auxiliary generator having one pole thereof connected with the lead L of the main circuit, a horseshoe-magnet, around one leg of which is a coil, the ends of which are connected to the two leads of the main circuit, and around the other leg of which is a coil, one end of which is attached to the free pole of the said generator and the other end to the lead L, and an armature connected with the said pole to which the coil is attached, and adapted when moved by the magnet to form an electrical connection with the lead IP of the main circuit, as and for the purpose described.

U. In an automatic coupler for electrical generators, the combination of a main external circuit, an auxiliary generator, having one pole thereof connected with the corresponding lead of the main circuit, a horseshoemagnet, around one leg of which is a coil connected with the main external circuit, and around the other leg of which is a coil, one end of which is connected to the same lead I of the external circuit that is connected with one pole o't'the auxiliary generator, the other end of the said. coil being connected to the other pole of the generator, and an armature adapted to include the said generator in the main circuit when moved by the said magnet, as and for the purpose described.

7. In an automatic coupler for electrical generators, the combination of a main external circuit having two leads, L and L an auxiliary generator having one pole thereof connected with the said lead L, a horseshoemagnet, one leg of which is excited by a current derived from the main, circuit, and the other leg of which is excited by a current from the auxiliary generator, and an armature adapted when moved by the said magnet to include the said generator in the main circuit, as and for the purpose described.

CARL IIOFFMANN. [L. s]

Witnesses:

B. ROI, ARTHUR MARKs.

IIO 

